Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature resulting in right heart failure and death. Idiopathic and familial forms of PAH (iPAH and fPAH respectively) have a mean age at diagnosis of 35 years and a median survival of 2.8 years if untreated. Mutations in the bone morphogenetic protein receptor 2 (BMPR2) have been identified in at least 70% of FPAH patients. However, the penetrance of these BMPR2 mutations is 10- 20%, suggesting that genetic and/or environmental modifiers are required for disease expression. In addition, females are significantly over-represented amongst FPAH patients. Neither of these phenomena have been adequately explained and this conference will review and discuss recent research with a view to determining the major factors influencing disease penetrance. Basic research findings are intense and ongoing to find treatments for pulmonary arterial hypertension (PAH), highlighting the need for translational research which bridges the gap between lab bench discoveries and practical applications in the clinical realm. As such, it is important for researchers from both basic and clinical fields to meet in focused forums such as the Grover Conference. In the past decade, advances in PAH drug development have centered on factors that may be responsible for the increased penetrance in females and genetic and/or environmental modifiers that are required for disease expression in BMPR2 mutation carriers. These include estrogen metabolism, obesity, novel endogenous vasoactive factors and novel genetic loci interacting epistatically with BMPR2. Talks and poster presentations at this conference will review this rapidly developing field. The impact of genetic and environmental risk factors on the responsiveness of patients to current and emerging therapies will also be discussed. The 2011 Grover Conference brings together experts in the basic research fields of genetics, physiology, pharmacology, endocrinology, as well as clinical approaches dealing with drug development and the clinical management of PAH. Invited speakers include members of the ATS Pulmonary Circulation and Respiratory Cell and Molecular Biology Assemblies at the ATS representing active research groups studying the underlying cellular and molecular mechanisms of PAH. We have also invited key-note speakers from other relevant disciplines as PAH has a complex pathobiology and there are important lessons to be learned from other fields such as obesity, epigenetics, and cancer. Since its inauguration in 1984, the 2011 Grover Conference will be the 15th in this series, representing the longest-standing conference on the pulmonary circulation. Today it remains the principal conference for pulmonary vascular function.